This activity is designed to define the biotic and abiotic characteristics found in a rocky intertidal ecosystem, to observe interactions between select living organisms and between themselves and their environment, and analyze which environmental and competitive factors may influence the particular pattern of density, diversity, or zonation found at a study site. The transect method and statistical analysis used for sampling population abundance and diversity in this activity is applicable to many other coastal and terrestrial habitats. As a result of this activity students should be able to recognize the effect common physical and chemical factors have on rocky intertidal ecosystems, become familiar with the dominant inhabitants of rocky shores, recognize some of the most obvious adaptations of marine organisms to desiccation and wave action in rocky shores, recognize vertical zonation in rocky intertidal communities, and quantify species diversity and abundance.